Reverse engineering (RE) of integrated circuits (ICs) can be considered as one of the most serious threats to semi-conductor industry, since it may be misused by an attacker to steal and/or pirate a circuit design. An attacker who successfully reverse engineers an integrated circuit can fabricate and sell a similar, i.e. cloned, circuit and illegally sell and reveal the design. Therefore concepts and techniques that thwart reverse engineering of integrated circuits are desirable.